Rollup merge of #100822 - WaffleLapkin:no_offset_question_mark, r=scottmcm

Replace most uses of `pointer::offset` with `add` and `sub`

As PR title says, it replaces `pointer::offset` in compiler and standard library with `pointer::add` and `pointer::sub`. This generally makes code cleaner, easier to grasp and removes (or, well, hides) integer casts.

This is generally trivially correct, `.offset(-constant)` is just `.sub(constant)`, `.offset(usized as isize)` is just `.add(usized)`, etc. However in some cases we need to be careful with signs of things.

r? ````@scottmcm````

_split off from #100746_

4 files changed, 10 insertions, 10 deletions

diff --git a/library/std/src/sys/sgx/abi/usercalls/tests.rs b/library/std/src/sys/sgx/abi/usercalls/tests.rs
index 4320f0bccd1..58b8eb215d7 100644
--- a/library/std/src/sys/sgx/abi/usercalls/tests.rs
+++ b/library/std/src/sys/sgx/abi/usercalls/tests.rs
@@ -17,12 +17,12 @@ fn test_copy_to_userspace_function() {
             dst.copy_from_enclave(&[0u8; 100]);
 
             // Copy src[0..size] to dst + offset
-            unsafe { copy_to_userspace(src.as_ptr(), dst.as_mut_ptr().offset(offset), size) };
+            unsafe { copy_to_userspace(src.as_ptr(), dst.as_mut_ptr().add(offset), size) };
 
             // Verify copy
             for byte in 0..size {
                 unsafe {
-                    assert_eq!(*dst.as_ptr().offset(offset + byte as isize), src[byte as usize]);
+                    assert_eq!(*dst.as_ptr().add(offset + byte), src[byte as usize]);
                 }
             }
         }
diff --git a/library/std/src/sys/windows/alloc.rs b/library/std/src/sys/windows/alloc.rs
index fdc81cdea7d..fe00c08aa6a 100644
--- a/library/std/src/sys/windows/alloc.rs
+++ b/library/std/src/sys/windows/alloc.rs
@@ -168,7 +168,7 @@ unsafe fn allocate(layout: Layout, zeroed: bool) -> *mut u8 {
         // SAFETY: Because the size and alignment of a header is <= `MIN_ALIGN` and `aligned`
         // is aligned to at least `MIN_ALIGN` and has at least `MIN_ALIGN` bytes of padding before
         // it, it is safe to write a header directly before it.
-        unsafe { ptr::write((aligned as *mut Header).offset(-1), Header(ptr)) };
+        unsafe { ptr::write((aligned as *mut Header).sub(1), Header(ptr)) };
 
         // SAFETY: The returned pointer does not point to the to the start of an allocated block,
         // but there is a header readable directly before it containing the location of the start
@@ -213,7 +213,7 @@ unsafe impl GlobalAlloc for System {
 
                 // SAFETY: Because of the contract of `System`, `ptr` is guaranteed to be non-null
                 // and have a header readable directly before it.
-                unsafe { ptr::read((ptr as *mut Header).offset(-1)).0 }
+                unsafe { ptr::read((ptr as *mut Header).sub(1)).0 }
             }
         };
 
diff --git a/library/std/src/sys/windows/fs.rs b/library/std/src/sys/windows/fs.rs
index aed082b3e0a..1361b9c90c0 100644
--- a/library/std/src/sys/windows/fs.rs
+++ b/library/std/src/sys/windows/fs.rs
@@ -512,7 +512,7 @@ impl File {
                     ));
                 }
             };
-            let subst_ptr = path_buffer.offset(subst_off as isize);
+            let subst_ptr = path_buffer.add(subst_off.into());
             let mut subst = slice::from_raw_parts(subst_ptr, subst_len as usize);
             // Absolute paths start with an NT internal namespace prefix `\??\`
             // We should not let it leak through.
@@ -1345,10 +1345,10 @@ fn symlink_junction_inner(original: &Path, junction: &Path) -> io::Result<()> {
         let v = br"\??\";
         let v = v.iter().map(|x| *x as u16);
         for c in v.chain(original.as_os_str().encode_wide()) {
-            *buf.offset(i) = c;
+            *buf.add(i) = c;
             i += 1;
         }
-        *buf.offset(i) = 0;
+        *buf.add(i) = 0;
         i += 1;
         (*db).ReparseTag = c::IO_REPARSE_TAG_MOUNT_POINT;
         (*db).ReparseTargetMaximumLength = (i * 2) as c::WORD;
diff --git a/library/std/src/sys/windows/os.rs b/library/std/src/sys/windows/os.rs
index bcac996c024..352337ba322 100644
--- a/library/std/src/sys/windows/os.rs
+++ b/library/std/src/sys/windows/os.rs
@@ -99,11 +99,11 @@ impl Iterator for Env {
                 }
                 let p = self.cur as *const u16;
                 let mut len = 0;
-                while *p.offset(len) != 0 {
+                while *p.add(len) != 0 {
                     len += 1;
                 }
-                let s = slice::from_raw_parts(p, len as usize);
-                self.cur = self.cur.offset(len + 1);
+                let s = slice::from_raw_parts(p, len);
+                self.cur = self.cur.add(len + 1);
 
                 // Windows allows environment variables to start with an equals
                 // symbol (in any other position, this is the separator between